The Host-Microbe Core (HMC) has evolved from the original Cell Biology core which was intended to help DDRCC members study cell structure and function. This change coincided with the decision of past funding cycle to intensify the DDRCC focus on IBD and IBD-related fields. In this regard, the study of the enteric microbiome and host-microbe interactions has come to the forefront of IBD research because of the increasing realization that it is a caused by an unfortunate combination of potentially disease-promoting commensal bacterial on a background of host genetic susceptibility. The development of the Host-Microbe core was therefore timely because it anticipated the growing needs of our investigators to better understand the complex interactions between host and gut microbes. Two of three original components of the Cell Biology Core were changed. Only the Cell/Tissue Systems component, which provides cells and cell-based systems for elucidation of mechanisms mediating cell-cell relationships, was retained. Most of the cell physiology component, including patch-clamp electrophysiology, was removed largely because of declining usage. The structural biology component was moved to the Tissue and Cell Analysis Core where all light and digital imaging technologies now reside. In their place, the gnotobiotic and enteric microbiology components have been added which provide new opportunities for investigators to comprehensively study host-microbe interactions. Both components incorporate new technologies, experimental models, and expertise that bear on the study of healthy gut as well as inflammatory bowel diseases and related disorders. Together, the components have significantly advanced the capabilities of our DDRCC investigators to study fundamental questions in human-based and experimental research. The Administrative Director of the HMC, Dr. Eugene Chang, oversees the operations of all components and also serves as the Director of the Cell/Tissue Systems component. Drs. Antonopoulos and Chervonsky direct the Enteric Microbiology and Gnotobiotic components, respectively. Directors are responsible for insuring proper scientific direction and the integration and efficient use of services and facilities of their respective components. In summary, the HMC is the most heavily used Core of the DDRCC. It has enabled our investigators to study previously unexplored aspects of host-microbial interactions, using a variety of cutting edge approaches that span from reductionist systems to in vivo models. The HMC is also vital to the translational research effort at the University of Chicago that has become prominent in the area of IBD.